What is a primary challenge of using Office 365 with legacy firewalls?

Using Office 365 with legacy firewalls presents significant challenges primarily due to the nature of how modern applications operate, particularly those like Office 365 that rely on persistent connections and long-lived sessions. Legacy firewalls are often designed to evaluate and manage traffic based on traditional packet or connection methods that can struggle with the consistent demands that Office 365 places on network resources.

When Office 365 applications establish long-lived sessions, they can consume numerous firewall ports. Each session might require its own connection, and as these sessions remain open for extended periods, they can exhaust the available ports on the firewall. This can lead to issues with connectivity, performance degradation, and ultimately impact user access to critical applications.

Therefore, effectively managing firewall resources becomes a paramount concern, making the integration of modern cloud applications like Office 365 challenging in environments that rely on legacy firewall architectures. Addressing these challenges typically necessitates a reevaluation of security strategies, moving towards solutions that are designed to handle cloud application traffic more effectively.